This species account is dedicated in honor of Scott Edwards, member of the Cornell Lab of Ornithology's Administrative Board.
One of the most common and numerous birds throughout much of the contiguous United States, southern Canada, and Mexico, the House Finch is a bird of remarkable records. From a few California individuals released from a pet store in New York City in 1939, and through natural expansion of its western range, in just a few decades this species came to occupy one of the widest ecological ranges of any extant bird. Originally a bird of hot deserts and dry open habitats of the southwest, it now occurs in nearly all types of landscapes and climates in North America, from edges of northern taiga to ocean coasts to metropolitan areas.
Such dramatic expansion of ecological range has been associated with striking phenotypic diversification in morphology and physiology, enabling the persistence of this species under diverse ecological conditions. In 1994, the explosive growth of House Finch populations across North America was interrupted by one of the worst epizootics in history – an outbreak of mycoplasmosis that killed millions of individuals across the continent and drove many small populations to near extinction. The combination of local abundance and wide distribution, exceptional invasive and acclimation abilities, striking phenotypic variation (including carotenoid-based plumage ornamentation), ongoing evolution of disease resistance, and well-documented history of population fluctuations has made the House Finch one of North America's best studied birds.